Underwater propulsion unit



FIG. 1 is a perspective view of the underwater propulsion unit taken from the front, top and left side, showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof. 

The ornamental design for an underwater propulsion unit, as shown and described. 